JP2011109870A - Magnetic pole position estimation device of synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic pole position estimation device of a synchronous motor, capable of estimating an initial magnetic pole position of a rotor with high accuracy. <P>SOLUTION: The estimation device includes a phase calculation means adding a rotation amount of the rotor, which is obtained from pulse count of an encoder arranged in the synchronous motor, to an estimation value of the magnetic pole position and calculating a control phase when the rotor rotates after estimation of the magnetic pole position by an estimating means, and a pulse voltage application condition change means changing on-time of pulse voltage so that a difference of the control phases calculated by the phase calculation means just before and just after a reference signal of the encoder is input becomes within an allowable error which is previously set. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic pole position estimation device for a synchronous motor.

  In a synchronous motor, there has been proposed one that estimates the initial magnetic pole position of a rotor with a width of 60 electrical degrees based on the magnitude relationship between current peak values accompanying magnetic saturation when a pulse voltage is applied. Thereby, the synchronous motor is started without step-out, and stable operation is possible by performing magnetic pole correction by the induced voltage after the speed is increased (see, for example, Patent Document 1).

Japanese Patent No. 3663937

  However, in the thing of patent document 1, the initial magnetic pole position of a rotor is estimated only by the width | variety of an electrical angle of 60 degree | times. For this reason, there has been a problem that the estimation accuracy of the initial magnetic pole position of the rotor is poor in an application such as an elevator that requires delicate torque control and sufficient acceleration torque from the start of the synchronous motor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetic pole position estimation device for a synchronous motor that can accurately estimate an initial magnetic pole position of a rotor. .

  A magnetic pole position estimation device for a synchronous motor according to the present invention includes a voltage application unit that applies a voltage to each phase of the synchronous motor, a current detection unit that detects a current value flowing through each phase in response to the voltage, and 360 Storage means storing a plurality of voltage command vectors of the same amplitude having a phase difference obtained by equally dividing the degree, and a plurality of voltage commands for each phase based on the voltage command obtained by converting the voltage command vector into the voltage application means. Voltage control means for sequentially switching and applying the pulse voltage for estimating the magnetic pole position, and calculating a plurality of current vectors based on the amplitude of the current flowing in each phase in synchronization with the plurality of pulse voltages for estimating the magnetic pole position Estimating means for estimating a magnetic pole position of the rotor based on a phase of an average vector of the plurality of current vectors respectively responding to the plurality of voltage command vectors; and When the rotor rotates after the estimation of the magnetic pole position, the amount of rotation of the rotor obtained from the pulse count of the encoder provided in the synchronous motor is added to the estimated value of the magnetic pole position to control phase The pulse voltage on-time so that the difference between the control phases calculated by the phase calculation means immediately before and immediately after the input of the reference signal of the encoder is within a preset allowable error. And a pulse voltage application condition changing means for changing.

  According to the present invention, the initial magnetic pole position of the rotor can be estimated with high accuracy.

It is a basic block diagram of the part regarding the magnetic pole position estimation of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the magnetic pole position estimation method of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the magnetic pole position estimation result of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the pulse voltage which the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention applies. It is a figure for demonstrating the phase current response waveform which the current detection means of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention detected. It is a figure for demonstrating the alpha phase current response waveform of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the beta phase current response waveform of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the locus | trajectory of the current vector detected by the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the convergence calculation of the magnetic pole estimated value by the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a flowchart for demonstrating the magnetic pole position estimation procedure of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the latch means at the time of the reference signal input of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the estimation accuracy confirmation of the initial magnetic pole position of a rotor performed by the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a flowchart for demonstrating operation | movement of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 1 of this invention. It is a figure for demonstrating the estimation error of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 2 of this invention. It is a whole block diagram of the magnetic pole position estimation apparatus of the synchronous motor in Embodiment 2 of this invention.

  A mode for carrying out the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
First, the rotor magnetic pole position estimation method by the synchronous motor magnetic pole position estimation apparatus according to the present embodiment will be described with reference to FIGS.
1 is a basic configuration diagram of a portion related to magnetic pole position estimation of a synchronous motor magnetic pole position estimation apparatus according to Embodiment 1 of the present invention.
In FIG. 1, 1 is a synchronous motor. The rotor (not shown) of the synchronous motor 1 is made of a permanent magnet. The synchronous motor 1 has a plurality of phases. Specifically, the synchronous motor 1 has a U phase, a V phase, and a W phase. These phases are connected to the circuit means 2. This circuit means 2 comprises an inverter. The circuit means 2 functions as a voltage applying means for applying a voltage to each phase of the synchronous motor 1 based on a voltage command from the computing means 3. At this time, a current in response to the applied voltage flows in each phase of the synchronous motor 1. These currents are detected by the current detection means 4 and input to the calculation means 3. The calculating means 3 calculates the magnetic pole position based on the detected current value.

  With the above control, in the synchronous motor 1 to which a pulse voltage is applied based on the voltage command of the arithmetic means 3, when the phase of the magnetic pole of the rotor and the phase of the applied voltage are in the same direction, the magnetic flux and rotation caused by the current generated by the applied voltage The magnetic flux of the child is also in the same direction. For this reason, the magnetic flux total value becomes large, and magnetic saturation occurs in the motor core. And at the time of magnetic saturation, the winding inductance of the phase of the synchronous motor 1 becomes small. For this reason, the amplitude of the current flowing in the phase of the synchronous motor 1 appears greatly.

  On the other hand, when the phase of the magnetic pole of the rotor is opposite to the phase of the applied voltage, the magnetic flux generated by the current generated by the applied voltage and the magnet magnetic flux of the rotor are in different directions. For this reason, the total magnetic flux value becomes small, and magnetic saturation does not occur in the motor core. And at the time of nonmagnetic saturation, the winding inductance of the phase of the synchronous motor 1 becomes large. For this reason, the amplitude of the current flowing in the phase of the synchronous motor 1 appears small. That is, depending on the relationship between the phase of the magnetic poles of the rotor and the phase of voltage application, the degree of magnetic saturation of the motor core is different, and the amplitude of the current flowing through the phase of the synchronous motor 1 is different.

  In the present embodiment, the above phenomenon is used to estimate the initial magnetic pole position of the rotor. Hereinafter, a configuration unique to the present embodiment will be described. As shown in FIG. 1, the calculation unit 3 includes a storage unit 5 and an estimation unit 6. The storage means 5 stores a plurality of voltage command vectors having the same amplitude and having a phase difference obtained by equally dividing 360 degrees.

  Then, the arithmetic means 3 sequentially switches a plurality of magnetic pole position estimation pulse voltages to each phase of the synchronous motor 1 based on the voltage command obtained by converting the voltage command vector to the circuit means 2 when the rotor starts rotating. Function as voltage control means to be applied. At this time, the calculation means 3 outputs a voltage command to the circuit means 2 and outputs a trigger signal synchronized with the voltage command to the current detection means 4. Thereby, the current detection means 4 detects a current pulse flowing in each phase of the synchronous motor 1 in synchronization with the pulse voltage.

  The estimation means 6 calculates a current vector based on the amplitude of the current pulse. Thereafter, the estimating means 6 estimates the initial magnetic pole position of the rotor based on the phase of the average vector of the plurality of current vectors respectively responding to the plurality of voltage command vectors.

Next, the procedure of the method for estimating the initial magnetic pole position of the rotor will be described with reference to FIGS.
FIG. 2 is a diagram for explaining a magnetic pole position estimation method of the synchronous motor magnetic pole position estimation apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram for explaining the magnetic pole position estimation results of the synchronous motor magnetic pole position estimation apparatus according to Embodiment 1 of the present invention.

  2A and 2B show an α-β coordinate system and a motor coordinate system. The α-β coordinate system is a fixed coordinate system. Specifically, the α-β coordinate system is represented by an orthogonal α axis and β axis. The motor coordinate system is a rotational coordinate system corresponding to the rotor. Specifically, the motor coordinate system is expressed by orthogonal d-axis and q-axis. In the following, the phase difference between the motor coordinate system and the fixed coordinate system is to be estimated.

First, in the α-β coordinate system, a pulsed pilot voltage is applied at a phase angle of 0 (deg). In FIG. 2A, the pilot voltages are V _α = V _p and V _β = 0. At this time, the following voltages (1) and (2) are applied on the motor coordinate system.
V ′ _d1 = V _p × cos θ ₁ (1)
V ′ _q1 = V _p × sin θ ₁ (2)

Then, as shown in FIG. 2B, the motor current response I _α1 to the pilot voltage,
I _β1 is represented by the following formulas (3) and (4).
I _α1 = I _α11 + I _α12 = I ′ _d1 × cos θ ₁ + I ′ _q1 × sin θ ₁ (3)
I _β1 = I _β11 + I _β12 = I ′ _d1 × sin θ ₁ + I ′ _q1 × cos θ ₁ (4)
However,
I ′ _d1 = {1 / (R _a + pL _d )} V ′ _d1
I ′ _q1 = {1 / (R _a + pL _q )} V ′ _q1
It is. R _a is an armature winding resistance, p is a differential operator, L _d is a d-axis inductance, and L _q is a q-axis inductance.
As shown in the equations (3) and (4), the motor current responses I _α1 and I _β1 include information on the phase difference θ ₁ between the motor coordinate system and the α-β coordinate system. Therefore, for example, when the d-axis of the motor coordinate system and the pilot voltage vector are close to each other, I ′ _d1 increases.

The above calculation is repeated every 60 (deg) with the phase of the pilot voltage being 0 to 300 (deg).
The pilot voltage at this time is expressed by the following equations (5) and (6).
V ′ _{α (n + 1)} = V _p × cos (0 + 60 × n) (5)
V ′ _{β (n + 1)} = V _p × sin (0 + 60 × n) (6)
However, n = 0-5.

Further, motor current responses I _αn and I _{βn at} this time are expressed by the following equations (7) and (8).
I _{α (n + 1)} = I _{α (n + 1) 1} + I _{α (n + 1) 2}
= I ′ _{d (n + 1)} × cos θ ₁ + I ′ _{q (n + 1)} × sin θ ₁ (7)
_{Iβ (n + 1)} = _{Iβ (n + 1) 1} + _{Iβ (n + 1) 2}
= I ′ _{d (n + 1)} × sin θ ₁ + I′q _{(n + 1)} × cos θ ₁ (8)
However,
I ′ _{d (n + 1)} = {1 / (R _a + pL _d )} V ′ _{d (n + 1)}
I ′ _{q (n + 1)} = {1 / (R _a + pL _q )} V ′ _{q (n + 1)}
n = 0-5.

Next, integrated values I _αsum and I _{βsum of the} current responses I _{α1 to} I _α6 and I _{β1 to} I _β6 with respect to the 6-pulse pilot voltage are calculated. These I _αsum and I _βsum are _expressed by the following equations (9) and (10).

Finally, arc tangent θ * of I _αsum and I _βsum is obtained. This arc tangent θ * is expressed by the following equation (11).
θ * = tan ⁻¹ (I _βsum / I _αsum ) (11)
This arc tangent θ * is estimated as the phase difference between the motor coordinate system and the fixed coordinate system. Based on this phase difference, the initial magnetic pole position of the rotor is estimated. Here, in FIG. 3, the arc tangent θ * is indicated by 7. As shown in FIG. 3, the arc tangent θ * and the phase difference between the motor coordinate system and the fixed coordinate system substantially coincide. That is, the initial magnetic pole position of the rotor is also estimated with high accuracy.

Next, a method for estimating the initial magnetic pole position of the rotor will be described in more specific examples with reference to FIGS.
FIG. 4 is a diagram for explaining the pulse voltage applied by the magnetic pole position estimating apparatus for a synchronous motor according to Embodiment 1 of the present invention.

  FIG. 4 shows voltage command vectors V1 to V6. These voltage command vectors have a phase difference obtained by equally dividing 360 degrees into six. Specifically, V1, V3, and V5 are set to match the U phase, V phase, and W phase of the synchronous motor 1, respectively. V2, V4, and V6 are set to match the intermediate phase between adjacent phases among these phases. A pulse voltage corresponding to these voltage command vectors is applied to each phase of the synchronous motor 1.

FIG. 5 is a diagram for explaining the phase current response waveform detected by the current detection means of the magnetic pole position estimation device for the synchronous motor according to Embodiment 1 of the present invention.
In FIG. 5, the horizontal axis represents time, and the vertical axis represents the current value. Here, 8 is a current value flowing in the U phase. Reference numeral 9 denotes a current value flowing in the V phase. The on-time of the pulse voltage is set for each electric motor so as to obtain a magnetic saturation current. In FIG. 5, the time is set to 400 (μsec).

  The off voltage between adjacent pulse voltages is arbitrarily set so that current waveforms between adjacent pulse voltages do not overlap. The zero voltage at the time of switching the pulse voltage is generated by turning off all the gates of the switching elements of each phase of the synchronous motor 1. In FIG. 5, the time is set to 2.4 (msec).

  Furthermore, the estimated time of the initial magnetic pole position of the rotor is set so as to satisfy a predetermined requirement. For example, when used for an elevator, the estimation of the initial magnetic pole position of the rotor is set to end before the brake is released. Specifically, in FIG. 5, the time is set to 20 (msec). Here, the current corresponding to V1 appears as a waveform having a predetermined polarity and peak value at about 0.003 (sec). Similarly, currents corresponding to V2 to V6 also appear as waveforms having a predetermined polarity and peak value at a predetermined time point.

  FIG. 6 is a diagram for explaining an α-phase current response waveform of the magnetic pole position estimation device for a synchronous motor according to Embodiment 1 of the present invention. FIG. 7 is a diagram for explaining a β-phase current response waveform of the synchronous motor magnetic pole position estimation apparatus according to Embodiment 1 of the present invention. The horizontal and vertical axes in FIGS. 6 and 7 are the same as those in FIG.

Here, 10 is the current value I _α converted from Iu and Iv to the α-β coordinate system. Further, 11 is a current value I _beta converted into alpha-beta coordinate system Iu and Iv.
As shown in FIGS. 6 and 7, I _α and I _β are expressed as values having peak values at the same time as Iu and Iv. This peak value is detected as the amplitude of the current when the pulse voltage is applied.

FIG. 8 is a diagram for explaining the locus of the current vector detected by the magnetic pole position estimating device for the synchronous motor according to Embodiment 1 of the present invention.
In FIG. 8, the horizontal axis indicates the current value 10 of Iα, and the vertical axis indicates the current value 11 of Iβ. Here, the tip of the current vector 12 corresponding to each pulse voltage is indicated by a square. The integrated value of these current vectors 12, that is, the tip of the average vector 13 is indicated by a triangle. In FIG. 8, the current vector 12 in the d-axis direction extends, and the average vector 13 also indicates the d-axis direction.

FIG. 9 is a diagram for explaining the convergence calculation of the estimated magnetic pole value by the synchronous motor magnetic pole position estimating apparatus according to the first embodiment of the present invention.
In FIG. 9, the horizontal axis represents time, and the vertical axis represents the U-phase current value and the estimated value of the initial magnetic pole position. FIG. 9 shows a convergence calculation result of the current value 8 flowing in the U phase and the phase 7 of the average vector 13.
As shown in FIG. 9, after 0.22 (sec), it is confirmed that the phase of the average vector 13 has converged at a value of slightly over 60 degrees. The convergence calculation time is arbitrarily set after confirming the convergence state.

Next, the operation of the magnetic pole position estimation apparatus will be described with reference to FIG.
FIG. 10 is a flowchart for explaining the magnetic pole position estimation procedure of the synchronous motor magnetic pole position estimation apparatus according to Embodiment 1 of the present invention. FIG. 10 shows a series of operations shown in FIGS.

First, in step S1, a pulse voltage for estimating the magnetic pole position is applied to the phase of the synchronous motor 1, and the process proceeds to step S2. In step S2, current values Iu and Iv flowing in the U phase and the V phase are detected, and the process proceeds to step S3. In step S3, the current values Iu and Iv are converted into the current values I _α and I _β in the α-β coordinate system, and the process proceeds to step S4. In step S4, the current value I.alpha, the maximum value _{I N.alpha} of I beta, _{I N.beta} is detected, the process proceeds to step S5.

In step S5, it is determined whether or not all six pulse voltages have been applied to the phase of the synchronous motor 1. If all six pulse voltages have not been applied, the process returns to step S1. On the other hand, if all six pulse voltages have been applied, the process proceeds to step S6. In step S6, the current value I _alpha, a maximum value _{I N.alpha} of I _beta, current accumulated value _{I0 (I} 0α, _I 0β) of _{I N.beta} is calculated, the process proceeds to step S7. In step S7, an estimated value of the initial magnetic pole position of the rotor is obtained by convergence calculation.

  According to the basic configuration, the initial magnetic pole position of the rotor is estimated based on the phase of the average vector 13 of the plurality of current vectors respectively responding to the plurality of voltage command vectors. Therefore, the initial magnetic pole position of the rotor can be estimated with higher accuracy than the width of every electrical angle of 60 degrees.

  However, in the case of only the basic configuration described above, it is necessary to perform a basic test for each synchronous motor 1 in order to set the on time of the pulse voltage so that a current that can be magnetically saturated flows. Further, only with the above basic configuration, the estimation accuracy of the initial magnetic pole position of the rotor cannot be confirmed. Therefore, in the present embodiment, the automatic adjustment of the on-time of the pulse voltage and the estimation accuracy confirmation of the initial magnetic pole position of the rotor can be performed. Hereinafter, the overall configuration of the magnetic pole position estimation device for the synchronous motor 1 according to the present embodiment will be described.

FIG. 11 is an overall configuration diagram of a magnetic pole position estimating device for a synchronous motor according to Embodiment 1 of the present invention.
In FIG. 11, 14 is an encoder. The encoder 14 is provided in the synchronous motor 1. The encoder 14 has a function of outputting A and B phase signals at predetermined intervals. The encoder 14 has a function of outputting a reference signal for only one pulse at a mechanical angle of 360 degrees. Reference numeral 15 denotes phase calculation means. This phase calculation means 15 has a function of calculating the current control phase by adding the magnetic pole position estimated by the estimation means 6 and the rotation amount of the rotor based on the pulse counts of the A and B phase signals output from the encoder 14. Prepare.

  Reference numeral 16 denotes a current controller. This current controller 16 is conventionally provided. The current controller 16 has a function of inputting the current detection value detected by the current detection means 4 and the current control phase calculated by the phase calculation means 15. The current controller 16 has a function of outputting a voltage command based on the detected current value and the current control phase to the circuit means 2. Reference numeral 17 denotes latch means for inputting a reference signal. The reference signal input latch means 17 has a function of latching the current control phase θ1 immediately before the input of the reference signal of the encoder 14 and the current control phase θ2 immediately after the input.

  On the other hand, in addition to the storage unit 5 and the estimation unit 6, the calculation unit 3 includes an error detection unit 18, an error storage unit 19, an error average calculation unit 20, an error tolerance storage unit 21, a pulse width determination unit 22, and a pulse voltage application. Condition change means 23 is provided. Further, in FIG. 11, the voltage control means 24 is clearly shown as one means of the calculation means 3.

  The error detection means 18 has a function of calculating the difference between the current control phases θ1 and θ2 latched by the reference signal input latch means 17. The error storage means 19 has a function of storing the difference calculated by the error detection means 18 each time when the rotor magnetic pole position is estimated a plurality of times a specified number of times. The error average calculation means 20 has a function of calculating the average value of the differences between the current control phases θ1 and θ2 stored in the error storage means 19. The error tolerance storage means 21 has a function of storing a preset tolerance range.

  The pulse width determination means 22 determines whether or not the average value of the differences between the current control phases θ1 and θ2 calculated by the error average calculation means 20 is within the allowable error range stored in the error allowable value storage means 21. It has a function to do. Further, when the average value of the differences between the current control phases θ1 and θ2 is within the allowable error range, the pulse width determination unit 22 determines the pulse voltage on-time set value at that time as the value of the storage unit 5. It has a function. The pulse voltage application condition changing unit 23 has a function of changing the ON time of the pulse voltage stored in the storage unit 5 when the average value of the differences between the current control phases θ1 and θ2 is outside the allowable error range.

Next, the estimation error of the initial magnetic pole position of the rotor will be described with reference to FIG.
FIG. 12 is a diagram for explaining the current control phase latched by the reference signal input latch means of the synchronous motor magnetic pole position estimating apparatus according to the first embodiment of the present invention.
In FIG. 12, the horizontal axis represents time, and the vertical axis represents the current control phase. The current control phase is incremented or decremented from the rotational direction of the synchronous motor 1. Here, the case of increment will be described.

  In general, as the number of rotor pole pairs increases, the numerical value of mechanical angle per electrical angle decreases. Therefore, the encoder 14 does not always output the reference signal while the rotor rotates by an amount corresponding to the electrical angle of 360 degrees. That is, until the reference signal is input, only the rotation amount of the rotor is known, and the absolute position of the rotor is determined only by the input of the reference signal. Then, it is necessary to correct the current control phase by determining the absolute position of the rotor. This correction value means an estimation error of the magnetic pole position of the rotor. This correction value can be obtained from the difference between the current control phase θ1 immediately before the input of the reference signal and the current control phase θ2 immediately after the input.

Next, the estimation accuracy confirmation of the initial magnetic pole position of the rotor performed by the pulse width determination means 22 will be described with reference to FIG.
FIG. 13 is a diagram for explaining estimation accuracy confirmation of the initial magnetic pole position of the rotor, which is performed by the magnetic pole position estimating device for a synchronous motor according to Embodiment 1 of the present invention.
On the left side of FIG. 13, 25 is the upper limit (γ) of the allowable error. Reference numeral 26 denotes a lower limit (−γ) of an allowable error. Reference numeral 27 denotes a difference between the current control phases θ1 and θ2. On the right side of FIG. 13, reference numeral 28 denotes an average value of the difference 27 between the current control phases θ1 and θ2.

  As shown on the left side of FIG. 13, any difference 27 falls within the allowable error ± γ. Therefore, as shown on the right side of FIG. 13, the average value 28 of the difference 27 is also within the allowable error range. In this case, the estimation accuracy of the initial magnetic pole position of the rotor is ensured, and it is determined that a sufficient amount of current is generated to generate magnetic saturation. Although not shown, when the average value of the difference 27 is outside the allowable error range, the estimation accuracy of the initial magnetic pole position of the rotor is not secured, and a sufficient amount of current to generate magnetic saturation is obtained. It is judged that it is not.

Next, a series of operations of the magnetic pole position estimation apparatus of the present embodiment will be specifically described with reference to FIG.
FIG. 14 is a flowchart for explaining the operation of the magnetic pole position estimating apparatus for a synchronous motor according to Embodiment 1 of the present invention.
First, as described in steps S1 to S7 in FIG. 10, the initial magnetic pole position of the rotor is estimated, and the process proceeds to step S8. In step S8, the synchronous motor 1 is started, and the process proceeds to step S9. In step S9, the process waits for the input of the reference signal from the encoder 14 and then proceeds to step S10.

  In step S10, the current control phases θ1 and θ2 immediately before and after the reference signal input are latched and acquired, and the process proceeds to step S11. In step S11, the difference between the current control phases θ1 and θ2 is calculated as the estimation error of the initial magnetic pole position of the rotor at the time of the current start, and the process proceeds to step S12. In step S12, the estimation error of the initial magnetic pole position of the rotor is stored, and the process proceeds to step S13. In step S13, a counter CNT (not shown) is counted up, and the process proceeds to step S14. In step S14, the synchronous motor 1 is stopped, and the process proceeds to step S15.

  In step S15, it is determined whether or not the counter CNT is equal to or greater than a preset designated number N. If the counter CNT is smaller than the specified number N, the process returns to step S1 and the above operation is repeated. On the other hand, when the counter CNT reaches the designated number N, the process proceeds to step S16. In step S16, the average value En of the estimation error is calculated, and the process proceeds to step S17. In step S17, it is determined whether or not the absolute value of the average value En of the estimation errors is smaller than the allowable error γ. When the absolute value of the average value En of the estimation errors is smaller than the allowable error γ, the process proceeds to step S18. In step S18, the on-time at that time is determined as the value of the storage means 5, and the operation ends.

  On the other hand, if the absolute value of the average value En of the estimation errors is larger than the absolute value of the allowable error γ in step S17, the process proceeds to step S19. In step S19, the ON time of the pulse voltage is set to be longer by a preset amount. For example, the ON time of the pulse voltage is set to be longer by one calculation cycle. At the same time, the counter CNT is reset and the operation from step S1 is repeated.

  According to the first embodiment described above, the initial magnetic pole position of the rotor is estimated based on the phase of the average vector 13 of the plurality of current vectors respectively responding to the plurality of voltage command vectors. For this reason, the initial magnetic pole position of the rotor can be estimated with higher accuracy than the width of each electrical angle 60.

  Further, the pulse voltage application condition changing unit 23 makes the difference between the current control phases θ1 and θ2 calculated by the phase calculating unit 15 immediately before and after the input of the reference signal of the encoder 14 fall within a preset allowable error. In addition, the ON time of the pulse voltage is changed. For this reason, it is possible to automatically set the ON time of the pulse voltage necessary for improving the estimation accuracy of the initial magnetic pole position of the rotor. That is, it is not necessary for the designer to tune each synchronous motor 1, and the design of the magnetic pole position estimation device can be omitted.

  Further, it is possible to easily check the estimation accuracy of the initial magnetic pole position of the rotor without requiring the encoder 14 with an absolute position detection function corresponding to the number of pole pairs. That is, even when the number of pole pairs is different in the newly designed synchronous motor 1, it is not necessary to make a prototype of the encoder 14 with an absolute position detection function, and cost and labor can be saved.

  Further, the pulse voltage application condition changing unit 23 turns on the pulse voltage so that the average value of the differences between the plurality of current control phases θ1 and θ2 obtained by performing the estimation of the magnetic pole position a plurality of times is within an allowable error. Change the time. For this reason, it is possible to allow variation in error that occurs when estimating the initial magnetic pole position of the rotor.

  In addition, the pulse voltage application condition changing means 23 increases the ON time of the pulse voltage by a preset amount when the average value of the differences between the current control phases θ1 and θ2 is outside the allowable error. As a result, the initial magnetic pole position of the rotor can be estimated with a pulse voltage having an on-time as short as possible.

  The synchronous motor 1 has three phases, and the estimation means 6 has an amplitude of a current flowing in two phases of the amplitude of a current flowing in the three phases of the synchronous motor 1 in synchronization with the pulse voltage for estimating the magnetic pole position. Is used to calculate the current vector and estimate the initial magnetic pole position of the rotor. For this reason, it is possible to easily and accurately estimate the initial magnetic pole position of the rotor by using the arithmetic means 3 used in normal motor control. Further, since no new device is required, the magnetic pole position estimation device can be reduced in size. Of course, it is also possible to calculate a current vector by detecting a current flowing in three phases.

  Further, the calculation means 3 matches the three phases of the voltage command vector with the three phases of the synchronous motor 1 and sets the other three phases of the voltage command vector between adjacent phases of the three phases of the synchronous motor 1. Set to the intermediate phase. For this reason, the voltage command to the circuit means 2 can be simplified. In addition, when the pulse voltage for estimating the initial magnetic pole position is switched, the calculation means 3 turns off all the gates of the switching elements of each phase and generates a zero voltage. For this reason, the estimation time of the initial magnetic pole position of the rotor can be shortened.

Embodiment 2. FIG.
FIG. 15 is a diagram for explaining an estimation error of the magnetic pole position estimation device for a synchronous motor according to Embodiment 2 of the present invention. FIG. 16 is an overall configuration diagram of a magnetic pole position estimating apparatus for a synchronous motor according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to Embodiment 1 and an equivalent part, and description is abbreviate | omitted.

  Usually, the easiness of magnetic saturation varies depending on individual manufacturing differences of the synchronous motor 1. In this case, as shown in FIG. 15, even if the average value 28 of the difference 27 between the current control phases θ1 and θ2 is outside the allowable error range, the average value 28 of the difference 27 between the current control phases θ1 and θ2 Can be considered to be stable in the estimation variation. Therefore, in the second embodiment, the average value 28 of the difference 27 is used as the offset value of the magnetic pole estimation position, thereby increasing the estimation accuracy of the magnetic pole position of the rotor.

  Specifically, in the magnetic pole position estimation apparatus in the second embodiment, as shown in FIG. 16, the maximum error value minimum value storage means 29, the correction value δ setting means 30 and the magnetic pole position estimation apparatus in the first embodiment Is added. The error maximum value / minimum value storage unit 29 has a function of extracting and storing the maximum value Emax and the minimum value Emin of the difference 27 between the current control phases θ1 and θ2 stored in the error storage unit 19. The correction value δ setting means 30 has the correction value δ set to 0 in the initial state.

  In the magnetic pole position estimation apparatus having such a configuration, when the difference between the maximum value Emax and the minimum value Emin is within twice the amplitude of the allowable error γ, the pulse width determination unit 22 supplies the correction value δ setting unit 30 with the correction value δ. Then, the average value 28 of the difference 27 between the current control phases θ1 and θ2 is reset. Then, the phase calculating device 15 calculates the control phase by adding the average value 28 of the difference 27 between the current control phases θ1 and θ2 together with the rotation amount of the rotor to the estimated value of the magnetic pole position.

  According to the second embodiment described above, even when the average value 28 of the difference 27 between the current control phases θ1 and θ2 is offset, the rotor is highly accurate without increasing the on-time of the pulse voltage. The initial magnetic pole position can be estimated.

  For example, in an elevator application, setting the ON time of the pulse voltage and correcting the estimated magnetic pole position with the correction value δ can be performed by performing several reciprocating operations at each floor stop operation at the installation stage. For this reason, the efficiency of the installation work of an elevator can be achieved.

1 synchronous motor, 2 circuit means, 3 calculation means, 4 current detection means,
5 storage means, 6 estimation means, 7 arc tangent θ *, 8-11 current value,
12 current vectors, 13 average vectors, 14 encoders,
15 phase calculation means, 16 current controller, 17 reference signal input latch means,
18 error detection means, 19 error storage means, 20 error average calculation means,
21 error tolerance storage means, 22 pulse width judgment means,
23 pulse voltage application condition changing means, 24 voltage control means, 25 upper limit of allowable error, 26 lower limit of allowable error, 27 difference of current control phases θ1, θ2,
28 average value of difference, 29 error maximum value minimum value storage means, 30 correction value δ setting means,

Claims (7)

Voltage application means for applying a voltage to each phase of the synchronous motor;
Current detection means for detecting a current value flowing in each phase in response to the voltage;
Storage means for storing a plurality of voltage command vectors of the same amplitude having a phase difference obtained by equally dividing 360 degrees;
Voltage control means for causing the voltage application means to sequentially switch and apply a plurality of magnetic pole position estimation pulse voltages to each phase based on a voltage command obtained by converting the voltage command vector;
Calculate a plurality of current vectors based on the amplitude of the current flowing in each phase in synchronization with the plurality of magnetic pole position estimation pulse voltages,
Estimating means for estimating a magnetic pole position of the rotor based on a phase of an average vector of the plurality of current vectors respectively responding to the plurality of voltage command vectors;
When the rotor rotates after the magnetic pole position is estimated by the estimating means, the rotation amount of the rotor obtained from the pulse count of the encoder provided in the synchronous motor is added to the estimated value of the magnetic pole position. Phase calculating means for calculating the control phase using
Change of pulse voltage application condition for changing the ON time of the pulse voltage so that the difference of the control phase calculated by the phase calculation means immediately before and after the input of the reference signal of the encoder is within a preset tolerance. Means,
A magnetic pole position estimation device for a synchronous motor, comprising:   The pulse voltage application condition changing means changes the ON time of the pulse voltage so that an average value of a plurality of the differences obtained by performing the estimation of the magnetic pole position a plurality of times is within the allowable error. 2. The magnetic pole position estimating apparatus for a synchronous motor according to claim 1, wherein   3. The magnetic pole position of the synchronous motor according to claim 2, wherein the pulse voltage application condition changing unit increases the ON time by a preset amount when the average value of the differences is outside the allowable error. Estimating device.   When the difference between the maximum value and the minimum value of the difference is within twice the amplitude of the allowable error, the phase calculation device calculates the average value of the difference together with the rotation amount of the rotor as an estimated value of the magnetic pole position. 4. The magnetic pole position estimation device for a synchronous motor according to claim 2, wherein the control phase is calculated by adding to the control phase. 5. The synchronous motor has three phases,
The estimation means calculates the current vector by coordinate conversion based on the amplitude of the current flowing in two phases of the amplitude of the current flowing in the three phases in synchronization with the pulse voltage for estimating the magnetic pole position. The magnetic pole estimation apparatus for a synchronous motor according to any one of claims 1 to 4. The storage means stores a plurality of voltage command vectors having the same amplitude having a phase difference obtained by equally dividing 360 degrees into six parts,
The voltage control unit matches the three phases of the voltage command vector with the phase of the three phases, and matches the other three phases of the voltage command vector with an intermediate phase between adjacent phases of the three phases. 6. The magnetic pole position estimating apparatus for a synchronous motor according to claim 5, wherein:   7. The voltage control unit according to claim 1, wherein when switching the pulse voltage for estimating the magnetic pole position, all the gates of the switching elements of each phase are turned off to generate a zero voltage. A magnetic pole position estimating device for a synchronous motor according to claim 1.

Images